An exhaustive quantitative structure-activity (QSAR) study of narcotic antagonists will be undertaken by use of the Hansch and the Free-Wilson approaches. Comparative analysis of narcotic agonists will provide information on possible differences in correlations for agonists and antagonists. Generally, partition, polar and steric factors will be the used parameters for the Hansch approach. Partition coefficients will be either calculated or determined whenever the need arises. Polar and steric parameters will be calculated from data available in literature. pKa and molar refraction, Mr data as well as characteristic distances, will be tried in the correlations. The number of series studied will be limited only by the availability of reliable biological data. The series to be considered include, but are not limited to, the following: benzomorphans, Diels-Alder adducts of Thebaine and Oripavine, morphine analogs, methadone analogs and meperidine analogs. Results obtained will be analyzed and used for prediction of better agents, especially antagonists.